The invention relates to a container assembly, with at least one stackable container which has a first engaging structure on its top and a second engaging structure on its underside, wherein the two engaging structures are matched to one another in such a way that, when two containers are resting on top of one another, the first engaging structure of the lower container lying on top, and the second engaging structure of the upper container lying below, engage in one another in such a way that the two containers are on the one hand secured against shifting relative to one another at right-angles to the stacking direction and on the other hand, due to rear-engaging elements of the engaging structures engaging from behind at right-angles to the stacking direction, there exists between the containers a locking which prevents lifting of the upper container from the lower container at least in certain areas.
A container assembly of this kind known from DE 44 09 411 A1 has a container in the form of a packing container which, with a sideways-oriented opening, ma be stacked vertically with others of its kind and also has means which facilitate the connection of containers resting on top of one another, to obtain a uniform, manageable container unit. These means which facilitate connection comprise amongst other things a first engaging structure located on the top and consisting of two rear hooks and two pin-like projections in the frontal area. Formed on the underside of the container is a second engaging structure made up of indentations or recesses, and so matched to the components of the first engaging structure that an upper container may be fitted on to a lower container in the course of a combined insert-and-turn process. The upper container is first of all placed at an angle, until the second engaging structure has hooked or engaged from behind with the hooks of the first engaging structure, then the front section of the upper container is lowered until, through the engagement of the projections, fixing secure from shifting is effected at right-angles to the stacking direction. The rear-engaging elements of the engaging structures comprised of hooks and their assigned recesses produce a reciprocal vertical fixing of the containers in the rear part of the containers. Corresponding fixing in the front part of the containers is effected by means of several additional connecting devices, which have coupling means in the form of rotating locking bolts and which may also be used simultaneously to hold in the closed position two side-mounted lid sides assigned to the container opening, after they have been placed on one another by suitable folding down.
A person using the container may easily be injured on the raised engaging structure exposed on the top of the container. This raised first engaging structure also obstructs the attachment of other containers which do not have a suitably matching second engaging structure. Another drawback is that, when the container is stood on an uneven surface, it cannot be stored safely due to its smooth underside, and that the lower container wall may be indented or damaged through irregularities of the floor.
Already known from EP 1 059 240 B1 is a container assembly in which stackable containers are equipped with connecting devices which have rotating locking bolts allowing vertical connection of stacked containers. The rotating locking bolts are in each case mounted rotatably on a bottom part of the container and may be rotated into a connected position reaching past a lid fitted on top and in which in each case they engage from behind an anchoring projection of the bottom part mounted above. On their undersides, the containers are equipped with raised feet which are able to dip into engaging recesses on the top of the container, so as to locate the stacked containers immovably at right-angles to the stacking direction. The feet are not involved in the vertical connection of the containers.
A similar container assembly is disclosed by EP 0 555 533 B1, in which however the coupling means of the connecting devices used for vertical interconnection are in the form of locking tabs pivotably mounted on the bottom part of the container.